The real question nowadays is, “Am I doing this for my own growth in ruchnius or am I doing it so that yenem will think I’m holy.” It seems to me that a lot of chumros are taken on because of what other people will say if we don’t follow the fashion.
The joke “Chumrah of the Month Club” sums it up. Back in the day people belonged to “clubs” that sent a copy of the currently most popular books to members at a reduced price, so members could be reading what everyone else was reading without paying too much. It strikes me that this is what’s going on now. It’s a lot easier to keep yoshon than to keep your temper. Being pleasant to your employees / co-workers / the taxi driver requires real self control of the kind that doing something that isn’t even halachically required doesn’t. And it’s really difficult to explain to your friends why you’re not jumping on the latest bandwagon.
So – it’s easier to get a reputation for being super-frum with an “easy” mitzvah bein adam l’makom than it is to be makpid on bein adam l’chavero when we really have to work at it.